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Running efficiency of LHR diesel has been confirmed by mean of well-known types of heat-insulating (HICs) or thermal barrier (TBCs) coatings. These materials are considered as a semitransparent media SHICs (STBCs) in the form of an ensemble of diffraction objects, forming own thermoradiative fields under the scattering theory laws. This problem is relevant for a diesel with combustion chamber (CC) in which intensive IR radiation reaches ~50% of total thermal flux. The authors indicate that predetermined selection of optical and thermoradiative parameters in the same spectrum for coatings (due to specific structural composition and porosity) can change their temperature fields inside its subsurface zone and hence in the CC gas volume. Previous author's research of optical parameters for ceramic semitransparent materials allowed offering SHIC (STBC) samples for rig testings.

The main objective of this research is the analysis of influence of optical and thermo radiating characteristics on the transient (steady state) temperature distributions inside the heat-insulating semitransparent (SHIC) и opaque (HIC) coatings for thermal regulation and control of walls and elements of the combustion chamber (CC) of high speed diesel engines. Developed author's methodology of physical and mathematical simulation of parameters of the radiant and heat conductivity transfer was used to calculate optimal balance of optical and thermo radiating characteristics of coatings - as selectively absorbing and scattering materials with different transmittance, reflection and emittance depending on wavelength diapasons of irradiating or radiating heat fluxes.

Heat-insulating coatings (HIC) being used in automotive industry for thermal insulation of thermally highly loaded components of combustion chamber (CC) are usually semitransparent (SHIC) for radiation of red-hot soot particles. The paper presents physical and mathematical models of radiation and conductive heat transfer and solution methods for multilayered scattering and absorbing coating. Calculations of radiation field are carried out by means of the method of moments and defined by the solution of differential equation system for moments of radiant intensity. The analysis is assumed to be without any soot layer on semitransparent one for this preliminary investigation. It allows to simulate temperature distributions for SHIC with internal radiant source above substrate with different reflection for operating conditions in CC of high-speed diesel engines (cyclic heating).

The paper considers the radiative heat exchange under intensive short (radiant flux of red-hot soot particles) and long (radiation of“hot" hydrocarbonic atmosphere) IR components of total thermal flux in the combustion chamber (CC) of high-speed diesel engines. The analysis is conducted for only one spectral band in the ceramic coating and is assumed to be without any soot layer on it for this preliminary investigation. Temperature distributions are calculated for two layer coating. It consists of a top layer based on the semitransparent heat-insulating coating (SHIC) with varios thickness and a bottom one (semitransparent or opaque which could be metal substrate) with variation of reflection for transient (one complete cycle of piston movement) and steady state (cyclic heating). The improved distributions of temperature due to volumetric radiant heat losses inside semitransparent and opaque heat-insulating coatings are discussed.

This work is about heat-insulating coatings (HIC) used for combustion chambers (CC) of Low-Heat-Rejection Diesel Engines. These semitransparent coatings provide the necessary thermal regime to boundary walls and elements of CC, generation make up 50% of the radiant heat flow component. For this purpose model samples of porous ceramic materials based on powders of zirconium, silicon, aluminum oxides were offered as selectively absorbing and scattering coatings. These materials have transparent bands within the range of radiation wavelengths of an ignited gas mixture in CC of high-speed diesel engines. Simulation results show that there is a subsurface temperature maximum for ceramics under intensive visible and short-range infrared radiation. Internal CC walls do not achieve these extreme temperatures using these coatings. This allows us to provide an optimum temperature mode for CC which limits formation of toxic nitrogen oxides and increases the engine efficiency.